Small 56.9 KB PDF for the 2SD1679, with an extra E suffix in the name that is not explained further. The 2SD prefix follows the JIS system and indicates an NPN bipolar transistor for low-frequency or power duty. The document most likely presents maximum ratings, characteristic curves and package outline. Use it to verify lead assignment and limits before fitting a replacement. Although catalogued as a schematic, it describes a single component rather than a board, and any PDF viewer opens it.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @cyberlanelectonik. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.